water in cylinders

[jody]

Hey guys I have a few questions for ya all. I've got a 2003 1900sr with a 4.3 MPI and got water in the cylinders on the port side. It seemed to happen after shutting the engine off the last time i was out. It started had when i restarted it to put it on the trailer. When i got it home i pulled the plugs to find the water. i have done a compression check and the numbers look ok. I am going to do a cylinder leak down test as soon as the tester arrives. I took the exhaust manifold and risers off to check them.(haven't done that yet but found the little flappers in the "Y" pipe are bad/folded over and broken.

My questions are
1. I have read that a bad/cracked manifold will allow water into the cylinders and even the oil (witch is the part i'm not sure of). Some say it will and some say it can't get into oil through the cylinders.
2. does that flapper really keep that much water from back flowing up the exhaust?

[mmwjr]

The flapper prevents a big surge of water from back flowing up the exhaust if you come off of plane to quickly. A more come source for this issue is a failed gasket between the exhaust manifold and riser or a bad riser. Do you boat in salt water and has the exhaust components ever been replaced? Water can get into the oil from the cylinder if you crank the engine over as the compression will force water pass the piston rings. Looks to see if the level is higher on the dipstick.

[shrew]

If you slow down too quickly and allow the wake to overtake you, with failed flappers, that can cause water ingress. Often exhaust pressure can offset some of this. If you anchored and take wake or waves on the stern and the flappers are failed, that can also lead to water ingress.

Old exhaust manifolds can corrode and allow water from the cooling passage into the exhaust passage.